水—荷载耦合作用下沥青混合料细观尺度域损伤特性研究

发布时间：2018-04-21 10:43

本文选题：沥青混合料 + 沥青砂浆　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：沥青路面是我国高速公路的主要结构形式,沥青混合料作为外部结构物,时刻与各种形态的水分接触,加之行车荷载的联合作用,致使材料内部的微缺陷逐渐萌生、扩展直至造成不可逆的材料或宏观力学性能的劣化,最终导致路面结构的破坏。需要注意的是,一方面,道路工程一直采用连续均质的方法研究沥青混合料的力学行为,这与沥青混合料本身的结构组成不符,未考虑细观特征对整体宏观性能的影响。另一方面,对于水对沥青路面材料的作用,人们往往联系为沥青路面的水损害,忽略了在形成水损害的过程中,由于水分存在对材料性能影响,加之荷载及周围环境的联合作用,沥青混合料材料性能的局部弱化和失效。因此,有必要将沥青混合料的细观结构特征考虑进来,分析在水分存在的情况下,荷载作用下的沥青混合料内部材料性能的局部损伤或失效。首先,基于工业X-ray CT扫描和数字图像处理技术,建立考虑真实细观结构的沥青混合料三维有限元模型,通过空隙率等体积指标验证了模型的组成正确性;基于沥青混合料三维重构成果,揭示了复杂孔隙结构下沥青混合料内部水分流动场的分布规律,获取了流速、饱和度等关键信息。其次,采用动态力学测试方法,对不同水环境下的典型级配沥青砂浆进行频率扫描试验和切口小梁三点弯曲试验,研究水分的存在对沥青砂浆材料性能的影响规律,并获取相关黏弹参数和断裂力学参数;基于水流场分布和水分对材料性能影响规律,采用扩展有限元方法(XFEM)分析荷载作用下沥青混合料的响应规律和局部损伤。结果表明,水分的存在会显著加剧沥青混合料的材料损伤。最后,以动态模量为评价指标研究水分的存在对沥青混合料整体材料性能的影响规律;以劈裂强度为评价指标研究长期浸水对沥青混合料整体材料性能的影响规律;与有限元模拟的结果相结合,研究细观尺度域下沥青混合料损伤规律。本文分析由于水分的存在对沥青混合料整体性能造成的影响,揭示在水-荷载耦合状态下沥青混合料的局部材料响应及损伤规律。为研究水对沥青混合料的作用提供了新思路,也为研究路面材料的破坏机理奠定基础。
[Abstract]:Asphalt pavement is the main structural form of highway in our country. As an external structure, asphalt mixture is always in contact with various forms of water, combined with the combined action of driving load, which results in the gradual initiation of micro-defects in the material. Expansion results in irreversible deterioration of material or macroscopic mechanical properties, which ultimately leads to pavement structure damage. It should be noted that, on the one hand, road engineering has been using the method of continuous homogeneity to study the mechanical behavior of asphalt mixture, which does not accord with the structural composition of asphalt mixture, and does not take into account the effect of meso characteristics on the overall macro performance. On the other hand, for the effect of water on asphalt pavement materials, people often relate to the water damage of asphalt pavement. Combined with load and surrounding environment, the local performance of asphalt mixture is weakened and invalidated. Therefore, it is necessary to take into account the meso-structural characteristics of asphalt mixture, and analyze the local damage or failure of the internal material performance of asphalt mixture under the condition of moisture. Firstly, based on industrial X-ray CT scanning and digital image processing technology, a three-dimensional finite element model of asphalt mixture considering real mesoscopic structure is established, and the validity of the model is verified by volume index such as voidage. Based on the results of 3D reconstruction of asphalt mixture, the distribution law of water flow field in asphalt mixture with complex pore structure is revealed, and the key information such as velocity and saturation are obtained. Secondly, using dynamic mechanical test method, the frequency scanning test and notch trabecular three-point bending test of typical graded asphalt mortar under different water environment are carried out to study the influence of moisture content on the performance of asphalt mortar. Based on the distribution of water flow field and the effect of water content on material performance, the response law and local damage of asphalt mixture under load are analyzed by extended finite element method (EFEM). The results show that the presence of moisture will significantly aggravate the material damage of asphalt mixture. Finally, the dynamic modulus is taken as the evaluation index to study the influence law of the existence of moisture on the performance of asphalt mixture, and the splitting strength is taken as the evaluation index to study the effect of long-term water immersion on the performance of asphalt mixture. Combined with the results of finite element simulation, the damage law of asphalt mixture in mesoscale range is studied. In this paper, the influence of moisture on the whole performance of asphalt mixture is analyzed, and the local material response and damage law of asphalt mixture under water-load coupling state are revealed. It provides a new way to study the effect of water on asphalt mixture and lays a foundation for studying the failure mechanism of pavement material.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U414

【参考文献】